The vehicle anti-theft devices most widely used are of the following three types: First, physical blocking, such as a steel rod with a lock fastened from brake pedal to steering wheel; second, electrical blocking to the ignition; and third, alarms.
These systems exhibit to greater or lesser extent the disadvantages that most are easily detectable and disconnectable, and most are not automatic.
One prior art system shuts off the fuel line, as well as having an ignition cutoff. This is the Model K 400 FS of Automotive Security Products. It is activated by a visible keypad, containing an owner code. A thief is immediately informed of the protection system by the keypad, and may simply substitute his keypad, with his code to operate the vehicle.